Spin excitations and spin wave gap in the ferromagnetic Weyl semimetal Co 3 Sn 2 S 2
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January 2021 Vol. 64 No. 1: 217062 https://doi.org/10.1007/s11433-020-1597-6
Editor’s Focus
Editor’s Focus
Spin excitations and spin wave gap in the ferromagnetic Weyl semimetal Co3Sn2S2 Chang Liu1,2†, JianLei Shen1,2†, JiaCheng Gao1,2†, ChangJiang Yi1,2, Di Liu1,2, Tao Xie1,2, Lin Yang1,2, Sergey Danilkin3, GuoChu Deng3, WenHong Wang1,4, ShiLiang Li1,2,4, YouGuo Shi1,2,4,5, HongMing Weng1,2,4,5* , EnKe Liu1,4* , and HuiQian Luo1,4* 1 Beijing
National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; 2 School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China; 3 Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organization, Lucas Heights NSW-2234, Australia; 4 Songshan Lake Materials Laboratory, Dongguan 523808, China; 5 Physical Science Laboratory, Huairou National Comprehensive Science Center, Beijing 101407, China Received May 31, 2020; accepted June 24, 2020; published online August 24, 2020
We report a comprehensive neutron scattering study on the spin excitations in the magnetic Weyl semimetal Co3 Sn2 S2 with a quasi-two-dimensional structure. Both in-plane and out-of-plane dispersions of the spin waves were revealed in the ferromagnetic state. Similarly, dispersive but damped spin excitations were found in the paramagnetic state. The effective exchange interactions were estimated using a semi-classical Heisenberg model to consistently reproduce the experimental T C and spin stiffness. However, a full spin wave gap below Eg = 2.3 meV was observed at T = 4 K. This value was considerably larger than the estimated magnetic anisotropy energy (∼0.6 meV), and its temperature dependence indicated a significant contribution from the Weyl fermions. These results suggest that Co3 Sn2 S2 is a three-dimensional correlated system with a large spin stiffness, and the low-energy spin dynamics can interplay with the topological electron states. magnetic Weyl semimetal, topological materials, spin excitations, neutron scattering PACS number(s): Citation:
71.55.Ak, 25.40.Fq, 75.30.Ds, 75.50.Gg
C. Liu, J. L. Shen, J. C. Gao, C. J. Yi, D. Liu, T. Xie, L. Yang, S. Danilkin, G. C. Deng, W. H. Wang, S. L. Li, Y. G. Shi, H. M. Weng, E. K. Liu, and H. Q. Luo, Spin excitations and spin wave gap in the ferromagnetic Weyl semimetal Co3 Sn2 S2 , Sci. China-Phys. Mech. Astron. 64, 217062 (2021), https://doi.org/10.1007/s11433-020-1597-6
1 Introduction Magnetic topological materials, which combine non-trivial band topology and magnetic order, have significant potential for fundamental physics and technology applications. This promise stems from a number of exotic quantum phenomena including the quantum anomalous Hall effect, topological *Corresponding authors (HongMing Weng, email: [email protected]; EnKe Liu, email: [email protected]; HuiQian Luo, email: [email protected]) † These authors contributed equally to this work. c The Author(s) 2020. This article is published with open access at l
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